A hematoma can be treated at home by following several easy techniques. Apply a cold compress shortly after injury to reduce the flow of blood slowing the formation of the hematoma. The cold compress should be applied for 15 minutes every hour for one to two days after injury. Elevate the injury above the heart to reduce the flow of blood to the hematoma. Rest the part of the body that sustained the injury to allow it to heal. Take an over-the-counter medication, like acetaminophen (Tylenol) to reduce pain and swelling.